Previously proposed systems of diathermy by exposure to radio frequency energy have not been satisfactorily successful in their applications to cancer therapy and other medical and industrial procedures because the prior systems do not efficiently heat lossy dielectric materials, do not deliver uniform cross-sectional heating, do not include self-supporting enclosure arrangements, produce excessive stray radiation, involve series resonance requiring an external capacitance connected in series with the diathermy coil, do not produce fields which are concentrated at the longitudinal center of the coil, and are not capable of delivering sufficient and uniform heat to deep-seated tumors.
The previously used diathermy systems are also unsatisfactory because they are not provided with an adequate limb or trunk-receiving diathermy therapy enclosure, do not provide uniform deep-heating in tissue (or other lossy dielectric material) undergoing diathermy treatment, do not concentrate the heat along a portion of the axis of the receiving enclosure, excessively heat surface tissue, and cause considerable discomfort to the patient.
Typical of these previously proposed systems are the devices disclosed in the following prior U. S. patents, found in a preliminary search of the prior art:
______________________________________ Wappler, 1,962,796 Story, 2,503,779 Gard, 2,515,211 Lindahl, 2,671,853 Porterfield et al, 3,375,468 Beeston, 3,408,598 Jakoubovitch, 3,571,644 Mettler, 3,747,013 ______________________________________